Unmanned aerial systems (UAS) employ a navigation system to determine a position or trajectory of an aircraft, such as an unmanned aerial vehicle (UAV). The navigation system uses a navigation model that combines measurements from an inertial navigation system (INS) of the UAV and absolute reference information from a global position system (GPS) to monitor the trajectory of the UAV. However, in some instances, GPS signals are not available or insufficient to obtain reliable data. In such an instance, the navigation system reverts to using a dead reckoning navigation technique, which relies solely on the measurements from the INS. However, measurements from the sensors of the INS are often noisy and introduce error into the navigation model. This error quickly propagates and causes the actual trajectory of the UAV to diverge from the estimated trajectory.